       IGraphExecutor
       (stop! [_] (err/unsupported!))
       (notify! [_] (err/unsupported!))
-      (include-vertex! [_ v] (err/unsupported!))
       (execute!
         [_]
         (let [t0     (now)

      IGraphExecutor
      (stop! [_] (err/unsupported!))
      (notify! [_] (err/unsupported!))
      (include-vertex! [_ v] (err/unsupported!))
      (execute!
        [_]
        (add-watch! g :remove-vertex watch-id


(defprotocol IGraphExecutor
  (execute! [_])
  (notify! [_])
  (stop! [_]))

(defn collect-pure
  [collect-fn]
